Year	Percent
1991	29.073
1992	28.3
1993	27.674
1994	27.697
1995	30.773
1996	29.952
1997	29.628
1998	30.849
1999	30.824
2000	30.601
2001	31.416
2002	31.54
2003	31.782
2004	31.86
2005	29.883
2006	28.974
2007	27.892
2008	27.27
2009	29.618
2010	27.424
2011	27.578
2012	26.351
2013	26.746
2014	27.147
2015	26.925
2016	27.826
2017	27.813
2018	27.744
2019	27.652
2020	27.569
2021	27.494
2022	27.411